Most metallurgical furnaces have at least one tapblock for the purpose of draining molten process material from the furnace. The process of draining molten process material from a metallurgical furnace via a tapblock is called tapping.
Tapblocks typically have a copper shell, cooling elements, refractory material and a tapping channel. The copper shell defines a hot face, which is the face of the tapblock that is positioned most closely to the molten process material inside the furnace, and a cold face, which is opposite the hot face. Because of the extreme heat of the molten process material contained within the furnace, the tapblock has one or more cooling elements to regulate the temperature of the inner refractory lining, tapping channel and the copper shell. The cooling elements are typically pipes adjacent to or surrounding the tapblock. A cooling fluid is pumped through the pipes.
Passing through the centre of the tapblock, and connecting the hot face and the cold face, is the tapping channel. The tapping channel is surrounded by one or more layers of refractory lining. The tapping channel is generally circular passage through which the molten process material flows during the tapping process. The cooling elements of the tapblock serve to extract heat from the refractory lining and the tapping channel.
When tapping is not in progress, the tapping channel is commonly plugged using heat resistant clay, or other suitable material. The clay plug remains in the tapping channel until tapping is required. When tapping becomes necessary, the clay plug must be removed from the tapping channel. In order to remove the clay plug, it is broken and removed in pieces using a tool called a thermal lance. A worker, referred to herein as a tapper, manually operates the lance and strikes the clay plug in an attempt to break the plug apart and to allow the molten process material to flow through the tapping channel. The tapper generally strikes the clay plug multiple times in an attempt to fully clear the tapping channel. In addition to tapping and lancing, in some processes, drilling is used to open the tapping channel.
During the lancing process, the tapper may inadvertently strike some of the refractory material lining the tapping channel along with the clay plug. Strikes from the lance can damage the refractory lining of the tapblock. In addition, the flow of molten metal through the tapping channel can gradually erode the refractory lining of the tapping channel leading to tapblock damage. Damaged tapblocks can present safety hazards and can lead to costly production downtime when they need to be replaced.
Therefore, there is a need for a system to monitor the tapping process, drilling process, and specifically the lancing process, and provide feedback in order to minimize damage to the tapblock or the refractory lining.